Beam collector electrode for high frequency tubes



BEAM COLLECTOR ELECTRODE FOR HIGH FREQUENCY TUBES Original Filed Aug. 6, 1959 2 Sheets-Sheet 1 INVENTOR ROBERT S. SYMONS ATTORNEY March 15, 1966 SYMQNS 3,240,982

BEAM COLLECTOR ELECTRODE FOR HIGH FREQUENCY TUBES Original Filed Aug. 6, 1959 2 Sheets-Sheet z iii 1 W02 i 3.

IN VENTOR F 3 ROBERT s. SYMONS ATTORNEY United States Patent 3,240,982 BAM (ISL-HECTOR ELECTRSDE FUR HTGH FREQUENQY TUBES Robert d. Symons, Los Altos, Califi, assignor to Varian Associates, Palo Alto, Calif., a corporation of California riginal application Aug. 6, 1959, Ser. No. 832,403, now Patent No. 3,169,206, dated Feb. 9, 1965. Divided and this application Aug. 20, 1962, Ser. No. 218,071

2 Qiaims. (Ci. 315-538) The present invention is a divisional application of my parent application U.S. Serial No. 832,402, filed August 6, 1959, and now issued as US. Patent No. 3,169,206 on February 9, 1965, and relates in general to high frequency tubes and more particularly to a novel high power, pulsed, UHF, broad band amplifier useful, for example, in applications as navigation and communication systems, as a driver for a linear accelerator, and the like.

The present invention encompasses two models of the novel high frequency high power klystron amplifier. The first model comprises a UHF seven cavity variably tuned klystron amplifier having a 45% R.F. efficiency and providing a 3% onehalf power bandwidth tunable over a 12% full power range. This tube is approximately nine feet long and including only the evacuated structure weighs approximately seven hundred pounds. The tube will deliver 8 megawatts peak RF. energy with an average power of approximately 30 kw.

T he other tube is a fixed tuned five cavity UHF klystron amplifier having a half power bandwidth of approximately 12% to 14% with an RF. efficiency of 32%. This tube is approximately eleven feet in length and including only the evacuated structure weighs approximate- 1y 700 pounds. The tube will deliver a UHF frequency 8 to megawatts peak RF. power with an average RF. power of kw.

The principal object of the present invention is to provide an improved high frequency ldystron amplifier tube apparatus which is relatively simple of construction, relatively easy to handle, and which will have long operating life while delivering high peak and high average RF. power.

One feature of the present invention is the provision of an extremely lightweight high thermal capacity beam collector having high velocity coolant flow therethrough to enhance heat transfer therein.

Other features and advantages of the present invention will become apparent upon a perusal of the following specification taken in connection with the accompanying drawings wherein,

FIG. 1 is a longitudinal view, partly in section, showing the multicavity klystron amplifier apparatus of the present invention,

FIG. 2 is an enlarged foreshortened view of a portion of the structure of FIG. 1 delineated by line 22,

FIG. 2a is an enlarged cross section view of a portion of the structure of FIG. 2 delineated by line 2a2a,

FIG. 2b is an enlarged cross sectional view of a portion of the structure of FIG. 2 delineated by line 2b2b,

FIG. 3 is a detail persective view of a portion of the structure of FIG. 2, delineated by line 3-3.

Referring now to FIG. '1 there is shown a longitudinal partly cross sectional view of a high frequency high power multicavity klystron tube apparatus utilizing features of the present invention. More specifically, the tube comprises an elongated tubular metallic envelope 1 having an electron gun assembly 2 at one end thereof for producing and directing the beam of electrons axially through the elongated vacuum envelope 1 to an electron collector assembly 3 mounted at the other end of the elongated amass? Patented Mar. 15, 1966 "ice envelope 1. A plurality of cavity resonators 4 are provided between the cathode assembly 2 and the collector assembly 3 for successive electromagnetic interaction with the beam of electrons passable therethrough.

A beam focusing solenoid 5 envelopes the central portion of the tubes envelope for focusing the electron beam throughout the length of the tube apparatus. The free end portion of the cathode assembly 2 is inserted within an oil tank 6 and sealed therewithin via suitable mating flanges provided on the tube envelope 1 and the oil tank 6. The oil in the oil tank serves to prevent electrical breakdown across the high voltage anode to cathode insulator of the cathode assembly 2.

Electromagnetic energy which it is desired to have amplified by the tube is fed to the first cavity 4 of the tube via coaxial line 7 and input loop 8. This RF. cr1- ergy serves to velocity modulate the beam, such velocity modulation being transformed into current density modulation as the beam travels down the length of the tube. The current density modulation is further enhanced by successive cavities 4. The current density modulation serves to excite the last or output cavity 4. The greatly amplified RF. output energy is extracted from the output cavity 4 via a suitable coupling iris 10 and hollow waveguide 9. The waveguide 9 is wrapped around the collector assembly 3. The output RF. energy is extracted from. the waveguide 9 via a coaxial line 11 and thence fed via a doorknob transition 12, having a cylindrical wave permeable window 13 vacuum sealed therein, to an output rectangular waveguide 14.

Referring now to FIGS. 1, 2 and 3 there is shown the lightweight high thermal capacity collector feature of the present invention. More specifically, a relatively thin wall hollow cylindrical collector bucket 91 is closed off at the far end thereof via a relatively thin transverse wall 92. The collector bucket 91 is adapted to receive the beam therein over the interior side walls thereof for dissipating the kinetic energies of the electrons. The collector bucket 91 including the end wall 92 is made of a good thermal conducting material as, for example, copper. The exterior of the collector bucket is provided with a plurality of relatively shallow channels 93 as of .100" deep milled therein (see FIG. 3).

The channels 93 are arranged such that there is a ct of four parallel directed channels extending around the collector bucket 91 as indicated by the arrows. More specifically, four parallel channels pass longitudinally along one side of the bucket from the closed end thereof substantially to the open end thereof, thence circumferentially through approximately of arc, thence passing longitudinally back to the closed end and diametrically across the closed end of the bucket and back longitudinally along the side of the bucket substantially to the open end thereof, thence circumferentially through approximately 90 of arc and thence longitudinally along side of the bucket to the closed end thereof. A plurality of parallel channels are employed to minimize turbulence in the flow of coolant.

The outside periphery of the channeled bucket 91 (see FIG. 2) is surrounded by a tightly fitting collector sleeve 94 thereby defining the coolant channels 93 between the milled out portions of the collector bucket 91 and the collector sleeve 94. The milled end wall 92 of the collector 91 is covered over by a cover plate 95 (see FIG. 2) having diametrically opposed slots cut in the outside periphery thereof for allowing coolant to communicate with the set of four parallel channels directed longitudinally of the collector bucket 91.

A centrally bored cylindrical block 96 is provided at the open end thereof with an outwardly directed flange 97 for sealing about its periphery to the end of the collector sleeve 94 (see FIG. 2b). The central bore of the cylin- 3 drical block 96 is provided with a longitudinally directed septum 98 sealed at one end to cover plate 95 thereby defining a coolant input manifold 99 and output manifold 101. Manifolds 99 and 101 connect to suitable coolant tubes via openings 102 and 103 in the metallic block 96.

The configuration and arrangement of coolant channels 93 on the collector bucket 91 facilitates easy manifolding of the collector as the input and output channels are closely spaced at the same end of the collector. In addition, maximum heat transfer to the flow of the coolant fluid is assured due to the high velocity flow of the coolant as of, for example, water. Moreover, the pattern of channel arrangement allows the close fiat end of the collector bucket 91 to be cooled without introducing excessive turbulence in the flow of coolant. Although the particular channel pattern shown includes only 4 longitudinal passes along the collector bucket, the number of such longitudinal passes N may be increased in steps of two While increasing the number of transverse end passes N in steps of one, the transverse end passes falling on paral lel chords of the circular end wall 92. Thus the pattern is defined by the following relationship: N =2N +2. The circumferal are between adjacent parallel channels sets is approximately 3 60/ N degrees.

The collector bucket 91 is supported from the tube body at the beam entrance thereto via the intermediary of an annular insulator 105 as of, for example, alumina ceramic (see FIG. 2a). The insulator 105 is, in turn, secured within an annular metallic channel 106- as of, for example, copper which is brazed to an annular header 107. The annular head 107 forms one pole piece of the solenoid and is made of a highly magnetic permeable material as of, for example, iron. The iron pole piece 107 is copper plated as it also forms one Wall of the output cavity 4.

The other end of the collector bucket 91 (see FIG. 2b) is supported from a coaxially disposed collector support cylinder 108 as of, for example, stainless steel through the intermediaries of annular frame members 109 and annular insulator 111. The other end of the collector support cylinder 108 is fixedly secured to the pole piece 107 as by, for example, welding. Insulators 105 and 111 serve to insulate the collector bucket 91 from the tube body such that the beam interception current on the tube body may be monitored as desired.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A high frequency tube apparatus including, means for producing and directing a beam of charged particles over a predetermined path longitudinally of the tube, means for collecting the beam at the terminating end of the beam path, means disposed along said beam path for producing successive electromagnetic interaction with the beam and for extracting high frequency Wave energy from said beam, a vacuum tight envelope enclosing the beam path, said beam collecting means including, a hollow beam collecting bucket closed at one end for receiving the charged particles of the beam along the interior wall surfaces thereof, said bucket having a shallow fluid coolant channel array on the outside surf-ace thereof, said channel passing array serving to pass fluid in a direction longitudinally along one side of said bucket from a first end substantially to a second end thereof N times, said channel array passing fluid across the closed end of said bucket N, times, and the pattern of said coolant channel array on said collector bucket satisfying the relationship N 2N +2, and means for confining the flow of fluid coolant to said channels whereby efficient cooling of said collector means is obtained in use.

2. A high frequency tube apparatus including, means for producing and directing a beam of charged particles over a predetermined path longitudinally of the tube, means for collecting the beam at the terminating end of the beam path, means disposed along said beam path for producing successive electromagnetic interaction with the beam and for extracting high frequency wave energy from said beam, a vacuum tight envelope enclosing the beam path, said beam collecting means including, a hollow beam collecting bucket closed at one end for receiving the charged particles of the beam along the interior wall surfaces thereof, said bucket having a shallow fluid coolant channel array 011 the outside surface thereof, said channel array comprising a subdivided main channel serving to pass coolant fluid in a direction longitudinally along one side of said bucket, said channel passing fluid in the reverse direction longitudinally along the side of said bucket in peripheral quadrature with the first channel, said channel also passing fluid across the closed end of said bucket to the opposite side of said bucket and thence down that side of the bucket longitudinally thereof, and thence back along the side of said bucket in a position which is in peripheral quadrature with the second and third longitudinal passes of said channel along said bucket, and means for confining the flow of fluid coolant to said channels whereby efiicient cooling of said collecting means is obtained in use.

References Cited by the Examiner UNITED STATES PATENTS 2,312,920 3/1943 Litton 3l336 X 2,440,245 4/ 1948 Chevigny 31321l X 2,843,795 7/1958 Bondley et al. 3l5-5.49 2,994,009 7/1961 Schmidt et al -3l312 X 3,104,338 9/1963 Symons 313-24 GEORGE N. WESTBY, Primary Examiner.

ROBERT SEGAL, Examiner. 

1. A HIGH FREQUENCY TUBE APPARATUS INCLUDING, MEANS FOR PRODUCING AND DIRECTING A BEAM OF CHARGED PARTICLES OVER A PREDETERMINED PATH LONGITUDINALLY OF THE TUBE, MEANS FOR COLLECTING THE BEAM AT THE TERMINATING END OF THE BEAM PATH, MEANS DISPOSED ALONG SAID BEAM PATH FOR PRODUCING SUCCESSIVE ELECTROMAGNETIC INTERACTION WITH THE BEAM AND FOR EXTRACTING HIGH FREQUENCY WAVE ENERGY FROM SAID BEAM, A VACUUM TIGHT ENVELOPE ENCLOSING THE BEAM PATH, SAID BEAM COLLECTING MEANS INCLUDING, A HOLLOW BEAM COLLECTING BUCKET CLOSED AT ONE END FOR RECEIVING THE CHARGED PARTICLES OF THE BEAM ALONG THE INTERIOR WALL SURFACES THEREOF, SAID BUCKET HAVING A SHALLOW FLUID COOLANT CHANNEL ARRAY ON THE OUTSIDE SURFACE THEREOF, SAID CHANNEL PASSING ARRAY SERVING TO PASS FLUID IN A DIRECTION LONGITUDINALLY ALONG ONE SIDE OF SAID BUCKET FROM A FIRST END SUBSTANTIALLY TO A SECOND END THEREOF N1 TIMES, SAID CHANNEL ARRAY PASSING FLUID ACROSS THE CLOSED END OF SAID BUCKET NT TIMES, AND THE PATTERN OF SAID COOLANT CHANNEL ARRAY ON SAID COLLECTOR BUCKET SATISFYING THE RELATIONSHIP N1=2NT+2, AND MEANS FOR CONFINING THE FLOW OF FLUID COOLANT TO SAID CHANNELS WHEREBY EFFICIENT COOLING OF SAID COLLECTOR MEANS TO OBTAINED IN USE. 